1. Field of the Invention
The present invention relates to an engine control device suitable for remotely operating the controlled section of an engine, particularly the shift or throttle system of a marine engine.
2. Description of the Related Art
The conventional engine control device suitable for remotely operating the shift and throttle systems of the marine engine includes a remote control box provided with an operation lever and mechanical force transmitting members such as the push-pull cables for connecting the output end of the control box to the controlled sections of the engine. When the distance extending from the control box to the controlled section becomes long, therefore, the push-pull cable must become long, too. This causes large frictional resistance to be created at the time when the operation lever is operated, and the extent to which the cable is extended becomes large accordingly. Particularly in the case of the control device provided with plural control boxes, large frictional resistance is caused at the time when the operation lever is operated, thereby making it difficult to operate the device.
In order to solve this problem, we inventors of the present invention have developed an engine control device provided with an actuator which is started and stopped responsive to electric signals. In the case of this engine control device, the movement of the operation lever is converted to electric signal by means of a sensor. This signal is applied to a drive unit through an electric cable. A motor which serves as the actuator is housed in the drive unit and the controlled section of the engine is driven by the rotation force of the motor.
In a case where this electric engine control device is provided with plural remote control boxes, only one effective control box selected by a selection switch can control the engine. These control boxes can be changed over from one to the other by the selection switch, if necessary. When the control boxes are to be changed over from one to the other, however, it is dangerous from the viewpoint of safety that the control boxes are not in neutral but other position.
When the operation lever is moved or shifted to forward or reverse position in the electric engine control device, dog clutches of the shift system are moved in the direction of their becoming toothed with each other by the rotation force of the motor. The clutches are not toothed with each other sometimes in this case by one operation of the lever, and when current is kept supplied to the motor, the clutches are sometimes left not toothed with each other. When the motor is stopped by the electric system damaged, the engine is left uncontrollable. In order to measure this emergency, it is desirable to have a backup system which enables the engine to be manually controlled, if necessary.